Application of Nanoparticles in Enhanced Oil Recovery: A Review of Recent Progress

Enhanced oil recovery (EOR) remains a critical strategy for maximising hydrocarbon extraction from mature reservoirs, where conventional primary and secondary methods typically leave 60–70% of original oil in place (OOIP). Nanoparticles—engineered materials with at least one dimension below 100 nm—have emerged as transformative EOR agents capable of simultaneously addressing the fundamental physicochemical limitations of conventional techniques. This review synthesises findings from over 230 peer-reviewed studies (2019–2026) and critically evaluates the performance of eight nanoparticle classes (SiO₂, Al₂O₃, TiO₂, ZnO, Fe₃O₄/Fe₂O₃, ZrO₂, graphene oxide, and CNTs) across thermal, chemical, and gas EOR methods. SiO₂ nanofluids demonstrated the highest wettability alteration efficiency (contact angle reduction of 80–110° on calcite), while Fe₃O₄ nanoparticles achieved the greatest asphaltene inhibition (80–92% efficiency). Nanocatalytic aquathermolysis using NiO/Fe₃O₄ reduced heavy crude viscosity by up to 93% at 240°C—28% superior to steam flooding alone. Nanoparticle-stabilised CO₂ and N₂ foams outperformed conventional surfactant foams by a factor of 5–8× in resistance factor, improving oil recovery by 23–35% OOIP. Nanoparticle–polymer hybrid systems retained >80% viscosity at 120°C and 100,000 ppm NaCl, surpassing standalone polymer flooding under harsh reservoir conditions. Synergistic nanoparticle–surfactant formulations reduced IFT to ultralow values (